This CL implements the first draft of Canvas 2D Context Attributes, aka getContext('2d', { alpha: f…

Source/core/html/canvas/Canvas2DContextAttributes.h

 /*
- * Copyright (c) 2010, Google Inc. All rights reserved.
+ * Copyright (c) 2013, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
  * copyright notice, this list of conditions and the following disclaimer
  * in the documentation and/or other materials provided with the
  * distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "config.h"
+#ifndef Canvas2DContextAttributes_h
+#define Canvas2DContextAttributes_h
 
 #include "CanvasContextAttributes.h"
+#include <wtf/PassRefPtr.h>
 
 namespace WebCore {
 
-CanvasContextAttributes::CanvasContextAttributes()
-{
-}
+class Canvas2DContextAttributes : public CanvasContextAttributes {

[jamesr, 2013/04/26 00:41:31]

WebGLContextAttributes has an alpha bit. why can't you just promote that up to
the base class?

[Stephen White, 2013/04/26 15:51:03]

On the C++ side, WebGLContextAttributes stores all its data in a
GraphicsContext3D::Attributes internally, so I'd have to pull it out of there
and change the callers to reference the new flag as well as the ::Attributes. I
don't see a big benefit to that.

On the IDL side, there is no base class between the two currently, so I think
that would have to be changed for both WebGL and Canvas at the spec level
(they're just two dictionaries that quack alike).

+public:
+    virtual ~Canvas2DContextAttributes();
 
-CanvasContextAttributes::~CanvasContextAttributes()
-{
-}
+    // Create a new attributes object
+    static PassRefPtr<Canvas2DContextAttributes> create();
+
+    // Whether or not the drawing buffer has an alpha channel; default=true
+    bool alpha() const;
+    void setAlpha(bool);
+
+protected:
+    Canvas2DContextAttributes();
+
+    bool m_alpha;
+};
 
 } // namespace WebCore
+
+#endif // Canvas2DContextAttributes_h